Nine speed automatic transmission

ABSTRACT

A multispeed automatic transmission is provided having four planetary gear sets, a plurality of friction and synchronizer clutches and two chain drive assemblies. The transmission is arranged along two parallel axes of rotation: a first axis defined by the input shaft and a second axis defined by the output shaft. The chain drive assemblies transfer power between sprockets disposed on the two axes. Various combinations of clutches may be engaged to provide nine forward speed ratios and five reverse speed ratios.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Ser. No. 12/105,819, nowU.S. Pat. No. 8,113,978 filed on Apr. 18, 2008 and as such, claimspriority thereto under 35 U.S.C. §120.

FIELD

The present disclosure relates to an automatic transmission for a motorvehicle and more particularly to a nine speed automatic transmission fora motor vehicle having four planetary gear sets and a plurality offriction and synchronizer clutches.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

Many current passenger car multiple speed automatic transmissionsinclude a combination of planetary gear sets and selectively engagedclutches and brakes which provide a plurality of forward torque or gearratios.

Whereas three and four speed automatic transmissions were oncecommonplace and considered suitable to provide the requisite flexibilityand performance, increasingly demanding economic and performance goalsas well as consumer preference continue to encourage automatictransmission research and development. One result of this effort hasbeen an increase in the number of available forward gears or speedratios provided by the transmission. Six, seven and eight speedautomatic transmissions are increasingly available.

Because they so closely match the power and torque curves of an engineto the vehicle speed and load, such six, seven and eight speedtransmissions provide significant performance enhancements and fueleconomies.

Study of these transmissions configurations, however, reveals thatimprovements are possible. For example, each of the selectively engagedfrictional couplings, i.e., the clutches and the brakes, contribute tofrictional losses, referred to as spin losses, when they are notengaged. Such spin losses are the result of relative rotation betweenthe multiple, interleaved plates or discs of such devices. Two primaryfactors influence spin losses: the size or torque capacity of the clutchor brake and the speed difference across the clutch or brake. Reducingsuch spin losses therefore provides improved transmission efficiencywhich is highly desirable.

SUMMARY

The present invention provides a nine forward speed automatictransmission for a motor vehicle which includes four planetary gearsets, a plurality of friction and synchronizing clutches and two chaindrive assemblies. The transmission is arranged along two parallel axesof rotation: a first axis defined by the input shaft and a second axisdefined by the output shaft. The chain drive assemblies transfer powerbetween sprockets disposed on the two axes.

Input torque is selectively provided to either a sun gear, a planetcarrier or a ring gear of a first, double pinion planetary gear set byengagement of one of three input clutches. The sun gear and the planetgear carrier are coupled to a respective pair of chain sprocketsdisposed on the input axis. A pair of chains transfer torque to arespective pair of chain sprockets disposed on the output axis. Thechain driven by the sun gear of the first, double pinion planetary gearset directly drives a sun gear of a second, simple planetary gear setthat, with a third, simple planetary gear set, acts as a firstsub-transmission. The chain driven by the planet gear carrier of thefirst, compound planetary gear set directly drives a sun gear of afourth, simple planetary gear set that acts as a secondsub-transmission. The transmission output is commonly connected to anddriven by a ring gear of the third, simple planetary gear set and aplanet gear carrier of the fourth, simple planetary gear set. Engagementof various combinations of the input clutches and a plurality ofsynchronizer clutches provides nine forward speeds and five reversespeeds.

It is thus an object of the present invention to provide an automatictransmission for motor vehicles which provides nine forward speeds.

It is a further object of the present invention to provide an automatictransmission for motor vehicles having an input shaft on a first axisand an output shaft and a second, offset, parallel axis.

It is a still further object of the present invention to provide anautomatic transmission for motor vehicles having four planetary gearsets and a plurality of friction and synchronizer clutches.

It is a still further object of the present invention to provide anautomatic transmission for motor vehicles having a pair of chain drivesconnecting components disposed on a pair of parallel, spaced apart axes.

Further objects, advantages and areas of applicability will becomeapparent from the description provided herein. It should be understoodthat the description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of the presentdisclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.Like reference numbers in the various Figures consistently refer to thesame element, component or feature.

FIG. 1 is a diagrammatic view of a first embodiment of a nine speedautomatic transmission according to the present invention;

FIG. 2 is a diagrammatic view of a second embodiment of a nine speedautomatic transmission according to the present invention;

FIG. 3 is a truth table presenting the various combinations of engagedclutches which achieve a given forward or reverse gear or speed ratio;and

FIG. 4 is a diagram illustrating the relationship between the physicalgears and the virtual or blended gears of a nine speed automatictransmission according to the present invention.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application or uses.

With reference to FIG. 1, a first embodiment of a nine speed automatictransmission according to the present invention is illustrated anddesignated by the reference number 10. The automatic transmission 10includes an input member or shaft 12 which is coupled to and driven by,for example, the output of an engine (not illustrated) or the turbine ofa torque converter (not illustrated). The transmission 10 also includesan output shaft 14 having first and second ends 16A and 16B. If thetransmission 10 is longitudinally mounted in a vehicle, one of the ends16A or 16B may be utilized to drive a final drive unit in the front orrear of a vehicle or both may be utilized to drive final drive units inthe front and rear of a vehicle. Alternatively, if the transmission 10is mounted transversely in a vehicle, either or both of the ends 16A and16B may be utilized to provide drive torque to either or both sides ofthe vehicle.

The automatic transmission 10 also includes a first, double pinionplanetary gear set or assembly 20 disposed about the axis of the inputshaft 12, a second, simple planetary gear set or assembly 30 disposedabout the axis of the output shaft 14, a third, simple planetary gearset or assembly 40 disposed about the axis of the output shaft 14 and afourth, simple planetary gear set or assembly 50 also disposed about theaxis of the output shaft 14.

The first, double pinion planetary gear assembly 20 includes a first sungear 22, a first planet gear carrier 24 and a first ring gear 26.Rotatably disposed in the first planet gear carrier 24 are a pluralityof pairs of inner and outer intermeshing first planet gears 28A and 28B,one pair of which is illustrated in FIG. 1. Each of the inner firstplanet gears 28A is in constant mesh with the first sun gear 22 and itsassociated outer first planet gear 28B and each of the outer firstplanet gears 28B is in constant mesh with the first ring gear 26. Thesecond, simple planetary gear assembly 30 includes a second sun gear 32,a second planet gear carrier 34 and a second ring gear 36. Rotatablydisposed in the second planet gear carrier 34 are a plurality of secondplanet gears 38, one of which is illustrated in FIG. 1. Each of theplurality of second planet gears 38 is in constant mesh with the secondsun gear 32 and the second ring gear 36.

The third, simple planetary gear assembly 40 includes a third sun gear42, a third planet gear carrier 44 and a third ring gear 46. Rotatablydisposed in the third planet gear carrier 44 are a plurality of thirdplanet gears 48, one of which is illustrated in FIG. 1. Each of theplurality of third planet gears 48 is in constant mesh with the thirdsun gear 42 and the third ring gear 46. The fourth, simple planetarygear assembly 50 includes a fourth sun gear 52, a fourth planet gearcarrier 54 and a fourth ring gear 56. Rotatably disposed in the fourthplanet gear carrier 54 are a plurality of fourth planet gears 58, one ofwhich is illustrated in FIG. 1. Each of the plurality of fourth planetgears 58 is in constant mesh with the fourth sun gear 52 and the fourthring gear 56. It should be noted that depending upon the desired gearratios to be provided by the fourth, simple planetary gear assembly 50,the plurality of fourth, single planet gears 58 may be replaced by pairsof meshing planet gears (not illustrated) creating a double pinionplanetary gear assembly.

The automatic transmission 10 also includes a first chain drive assembly60 having a first drive chain sprocket 62 disposed on the axis of theinput shaft 12, a first multiple link chain 64 and a first driven chainsprocket 66 disposed on the axis of the output shaft 14. Adjacent thefirst chain drive assembly 60 is a second chain drive assembly 70 havinga second drive chain sprocket 72 disposed on the axis of the input shaft12, a second multiple link chain 74 and a second driven chain sprocket76 disposed on the axis of the output shaft 14.

The automatic transmission 10 further includes a plurality of torquetransmitting devices such as friction clutches and synchronizerclutches. As utilized herein, the term “friction clutch” refers to atorque transmitting device having first and second pluralities ofinterleaved friction plates or discs which are compressed by anassociated operator or actuator and which is capable of carrying highlevels of torque, i.e., the actual torque carried by the automatictransmission 10. On the other hand, a “synchronizer clutch,” as utilizedherein, refers to a torque transmitting device having a limited torquecapacity synchronizer which is capable of carrying sufficient torque toovercome the inertia of an associated gear in order to synchronize itwith a shaft and a positive clutch such as a dog clutch which engages topositively couple the gear and shaft and which is capable of carryinghigh levels of torque. Furthermore, it should be understood that whilethese devices are referred to as synchronizer clutches which suggeststhat they synchronize and connect two rotating members, several of thesynchronizer clutches are, in fact, utilized as brakes, i.e., they slowand connect a rotatable member to a fixed or stationary member, therebyinhibiting rotation of the rotatable member. In the followingdescription, those synchronizer clutches functioning as brakes will benoted by the parenthetical addition of the word “brake.”

A first high torque capacity friction clutch 82 having, as noted,interleaved pluralities of friction clutch plates or discs is operablydisposed between and selectively connects the input shaft 12 and a firstshaft, quill or concentric member 102 which is coupled to and drives thefirst sun gear 22 of the first, double pinion planetary gear assembly 20and the second drive chain sprocket 72 of the second chain driveassembly 70. A second high torque capacity friction clutch 84 isoperably disposed between and selectively connects the input shaft 12and a second shaft, quill or concentric member 104 which is coupled toand drives the first planet gear carrier 24 of the first, double pinionplanetary gear assembly 20. The first planet gear carrier 24 of thefirst, double pinion planetary gear assembly 20 is, in turn coupled to athird shaft, quill or concentric member 106 which is coupled to anddrives the first drive chain sprocket 62 of the first chain driveassembly 60. A third high torque capacity friction clutch 86 is operablydisposed between and selectively connects the input shaft 12 to thefirst ring gear 26 of the first, double pinion planetary gear assembly20.

A first synchronizer clutch (brake) 88 having, as noted above, asynchronizer and positive clutch is operably disposed between andselectively connects or grounds the first ring gear 26 of the first,double pinion planetary gear assembly 20 to a stationary housing 108 ofthe automatic transmission 10. A second synchronizer clutch (brake) 90is operably disposed between and selectively connects or grounds to thestationary housing 108 a fourth shaft, quill or concentric member 110which is coupled to the second planet gear carrier 34 of the second,simple planetary gear assembly 30. A third synchronizer clutch (brake)92 is operably disposed between and selectively connects or grounds afifth shaft, quill or concentric member 112 which is coupled to both thesecond ring gear 36 of the second, simple planetary gear assembly 30 andthe third sun gear 42 of the third, simple planetary gear assembly 40.

A fourth synchronizer clutch 94 is operably disposed between andselectively connects a sixth shaft, quill or concentric member 114 tothe fourth shaft, quill or concentric member 110. The sixth shaft, quillor concentric member 114 couples the second sun gear 32 of the second,simple planetary gear set 30 and the second driven chain sprocket 72 ofthe second chain drive assembly 70. A fifth synchronizer clutch (brake)96 is operably disposed between and selectively connects or grounds thefourth ring gear 56 of the fourth, simple planetary gear assembly 50 tothe stationary housing 108. A sixth synchronizer clutch 98 is operablydisposed between and selectively connects the fourth ring gear 56 of thefourth, simple planetary gear assembly 50 to a seventh shaft, quill orintermediate member 116. The seventh shaft, quill or intermediate member116 interconnects the fourth sun gear 52 of the fourth, simple planetarygear assembly 50 and the first driven chain sprocket 66 of the firstchain drive assembly 60.

An eighth shaft, quill or concentric member 118 couples the secondplanet gear carrier 34 of the second, simple planetary gear assembly 30to the third planet gear carrier 44 of the third, simple planetary gearassembly 40. Alternatively, the eighth shaft, quill or concentric membermay be an extension of the fourth shaft, quill or concentric member 110.Similarly, extensions or portions of the output shaft 14 are coupled tothe third ring gear 46 of the third, simple planetary gear assembly 40and the fourth planet gear carrier 54 of the fourth, simple planetarygear assembly 50.

Inspection of the nine speed automatic transmission 10 just describedand illustrated in FIG. 1 reveals that the second and third planetarygear assemblies 30 and 40 and the second, third and fourth synchronizerclutches 90, 92 and 94 constitute a first sub-transmission A having aninput which is coupled to and driven by the second driven chain sprocket76 and an output which is coupled to and drives the output shaft 14. Thefirst sub-transmission A provides three speeds or gear ratios.Similarly, the fourth planetary gear assembly 50 and the fifth and sixthsynchronizer clutches 96 and 98 constitute a second sub-transmission Bhaving an input which is coupled to and driven by the first driven chainsprocket 66 and an output which is coupled to and drives the outputshaft 14. The second sub-transmission B provides two speeds or gearratios.

Referring now to FIG. 2, a second embodiment of the nine speed automatictransmission 10 according to the present invention is illustrated anddesignated by the reference number 10′. Upon examination, it will beappreciated that the second embodiment of the automatic transmission 10′includes all of the same active components, i.e., planetary gearassemblies and friction and synchronizer clutches and that thedifferences between the two embodiments relate to the arrangement of theactive components and shafts or concentric members associated with thesecond, third and fourth planetary gear sets or assemblies 30, 40 and50. In this regard, it should be noted that the arrangement of theactive components and shafts associated with the first, double pinionplanetary gear assembly 20 is the same in both embodiments.

Thus, the second embodiment nine speed automatic transmission 10′includes an input shaft 12′ and an output shaft 14′ having first andsecond ends 16A′ and 16B′.

A first, double pinion planetary gear assembly 20′ includes a first sungear 22′, a first planet gear carrier 24′, a first ring gear 26′ and aplurality of pairs of intermeshing first planet gears 28A′ and 28B′. Asecond, simple planetary gear assembly 30′ includes a second sun gear32′, a second planet gear carrier 34′, a second ring gear 36′ and aplurality of second planet gears 38′. A third, simple planetary gearassembly 40′ includes a third sun gear 42′, a third planet gear carrier44′, a third ring gear 46′ and a plurality of third planet gears 48′. Afourth, simple planetary gear assembly 50′ includes a fourth sun gear52′, a fourth planet gear carrier 54′, a fourth ring gear 56′ and aplurality of fourth planet gears 58′. Again, depending upon the desiredgear ratios to be provided by the fourth, simple planetary gear assembly50′, the plurality of fourth, single planet gears 58′ may be replaced bypairs of meshing planet gears (not illustrated) creating a double pinionplanetary gear assembly.

Arranged on the side of the first, double pinion planetary gear assembly20′ opposite the input shaft 12′ and between the second, simpleplanetary gear assembly 30′ and the fourth, simple planetary gearassembly 50′ are a first chain drive assembly 60′ and a second chaindrive assembly 70′. The first chain drive assembly 60′ includes a firstchain drive sprocket 62′, a first multiple link drive chain 64′ and afirst driven chain sprocket 66′. The second chain drive assembly 70′includes a second chain drive sprocket 72′, a second multiple link drivechain 74′ and a second driven chain sprocket 76′.

The second embodiment nine speed automatic transmission 10′ alsoincludes a first friction clutch 82′, a second friction clutch 84′ and athird friction clutch 86′ all of which are coupled to and driven by theinput shaft 12′. A first shaft or concentric member 102′ couples theoutput of the first friction clutch 82′ to the first sun gear 22′ of thefirst, double pinion planetary gear assembly 20′ and to the second chaindrive sprocket 72′. A second shaft or concentric member 104′ couples theoutput of the second friction clutch 84′ to the first planet gearcarrier 24′ of the first, double pinion planetary gear assembly 20′. Athird shaft or concentric member 106′ couples the first planet gearcarrier 24′ of the first, double pinion planetary gear assembly 20′ tothe first chain drive sprocket 62′. The output of the third frictionclutch 86′ is coupled to the first ring gear 26′ of the first, doublepinion planetary gear assembly 20′.

A first synchronizer clutch (brake) 88′ selectively connects or groundsthe first ring gear 26′ of the first, double pinion planetary gearassembly 20′ to a stationary housing 108′ of the automatic transmission10′. A second synchronizer clutch (brake) 90′ is coupled to a fourthshaft or concentric member 110′ and selectively grounds the secondplanet gear carrier 34′ of the second, simple planetary gear assembly 30to the stationary housing 108′. A third synchronizer clutch (brake) 92′selectively grounds a fifth shaft or concentric member 112′ which iscoupled to both the second ring gear 36′ of the second, simple planetarygear assembly 30′ and the third sun gear 42′ of the third, simpleplanetary gear assembly 40′. A fourth synchronizer clutch 94′selectively connects the fourth shaft or concentric member 110′ to asixth shaft or concentric member 114′ which is coupled to the second sungear 32′ of the second, simple planetary gear assembly 30′ and thesecond driven chain sprocket 76′. A fifth synchronizer clutch (brake)96′ selectively grounds the fourth ring gear 56′ of the fourth, simpleplanetary gear assembly 50′ to the stationary housing 108′. A sixthsynchronizer clutch 98′ selectively connects the fourth ring gear 56′ ofthe fourth, simple planetary gear assembly 50′ to a seventh shaft orconcentric member 116′ which is coupled to the fourth sun gear 52′ ofthe fourth, simple planetary gear assembly 50′ and the first drivenchain sprocket 66′.

The second embodiment of the nine speed automatic transmission 10′illustrated in FIG. 2 includes a first sub-transmission A′ encompassingthe second and third planetary gear assemblies 30′ and 40′ and thesecond, third and fourth synchronizer clutches 90′, 92′ and 94′ which iscoupled to and driven by the second driven chain sprocket 76′ and iscoupled to and drives the output shaft 14′. The first sub-transmissionA′ provides three speeds or gears ratios. Similarly, a secondsub-transmission B′ encompasses the fourth planetary gear assembly 50′and the fifth and sixth synchronizer clutches 96′ and 98′ which iscoupled to and driven by the first driven chain sprocket 66′ and iscoupled to and drives the output shaft 14′. The second sub-transmissionB′ provides two speeds or gear ratios.

Referring now to FIGS. 3 and 4, the operation of both embodiments 10 and10′ of the nine speed automatic transmission will be described. It willbe appreciated that the transmissions 10 and 10′ are capable oftransmitting torque from their input shafts 12 and 12′ to their outputshafts 14 and 14′ in nine forward speed, torque or gear ratios and fivereverse speed, torque or gear ratios. Each forward or reverse gear ratiois attained by activation or engagement of various combinations of twoor three of the clutches as will be explained below. FIG. 3 is a truthtable which presents the various combinations of friction andsynchronizer clutches that are activated or engaged to achieve thevarious forward and reverse gear ratios. Gear ratios and ratios stepsare also provided although it should be understood that these numericalvalues are presented for purposes of example and illustration only andthat such values may be adjusted over significant ranges to accommodatevarious applications and operational criteria of the automatictransmissions 10 and 10′.

In neutral, none of the clutch elements are activated or engaged.

In the lowest speed (highest gear ratio) reverse gear, denominated R1,the second friction clutch 84, the first synchronizer clutch (brake) 88and the second synchronizer clutch (brake) 90 are activated or engaged.

Moving to the next, higher speed (lower gear ratio) reverse gear,denominated R2, the second friction clutch 84 and the secondsynchronizer clutch (brake) 90 are deactivated or disengaged and thefirst friction clutch 82 and the fifth synchronizer clutch (brake) 96are activated or engaged while the first synchronizer clutch (brake) 88remains activated or engaged.

As higher speed reverse gears, e.g., R3, R4, etc., are selected andengaged, this process of friction and synchronizer clutch disengagementand engagement continues according to the truth table of FIG. 3. Notethat the first synchronizer clutch (brake) 88 remains activated orengaged in all five reverse gear ratios. It should be appreciated thatthe five reverse gear ratios are, in fact, those three pure gear ratiosprovided by the sub-transmission A and the two pure gear ratios providedby the sub-transmission B.

From neutral, first gear is achieved by activating or engaging the firstfriction clutch 82 and the second synchronizer clutch (brake) 90. Firstgear is an actual or pure gear ratio achieved by utilizing the lowestspeed gear (highest gear ratio) provided by the sub-transmission A.

Second gear is achieved by deactivating or disengaging the firstfriction clutch 82 and activating or engaging the third friction clutch86 and the fifth synchronizer clutch (brake) 96. As the truth table ofFIG. 3 presents, the second synchronizer clutch (brake) 90 remainsactivated or engaged. As illustrated in FIG. 4, second gear is a virtualor blended gear ratio achieved by mixing or blending the lowest speedgear (highest gear ratio) provided by the sub-transmission A and thelower speed gear (higher gear ratio) provided by the sub-transmission B.

Third gear is achieved by deactivating or disengaging the third frictionclutch 86 and the second synchronizer clutch (brake) 90 and maintainingactivation or engagement of the fifth synchronizer clutch (brake) 96.The second friction clutch 84 is activated or engaged. Third gear is anactual or pure gear ratio achieved by utilizing the lower speed gear(higher gear ratio) provided by the sub-transmission B.

Fourth gear is achieved by deactivating or disengaging the secondfriction clutch 84 and activating or engaging the third friction clutch86 and the third synchronizer clutch 92. Engagement or activation of thefifth synchronizer clutch (brake) 96 is maintained during the third gearto fourth gear shift and in fourth gear. Once again and as illustratedin FIG. 4, fourth gear is a virtual or blended gear ratio which isachieved by mixing or blending the lower speed gear (higher gear ratio)provided by the sub-transmission B with the middle speed gear (middlegear ratio) provided by the sub-transmission A.

Fifth gear is achieved by deactivating or disengaging the third frictionclutch 86 and the fifth synchronizer clutch (brake) 96 and activating orengaging the first friction clutch 82 while maintaining activation orengagement of the third synchronizer clutch (brake) 92. Fifth gear is anactual or pure gear ratio achieved by utilizing the middle speed gear(middle gear ratio) provided by the sub-transmission A.

Sixth gear is achieved by deactivating or disengaging the first frictionclutch 82 and activating or engaging the third friction clutch 86 andthe sixth synchronizer clutch 98 while maintaining activation orengagement of the third synchronizer clutch (brake) 92. As illustratedin FIG. 4, sixth gear is also a virtual or blended gear ratio which isachieved by mixing or blending the middle speed gear (middle gear ratio)of the sub-transmission A and the higher speed gear (lower gear ratio)of the sub-transmission B.

Seventh gear is achieved by deactivating or disengaging the thirdfriction clutch 86 and the third synchronizer clutch (brake) 92 andactivating or engaging the second friction clutch 84 while maintainingactivation or engagement of the sixth synchronizer clutch 98. Seventhgear is an actual or pure gear ratio achieved by utilizing the higherspeed gear (lower gear ratio) of the sub-transmission B.

Eighth gear is achieved by deactivating or disengaging the secondfriction clutch 84 and activating or engaging the third friction clutch86 and the fourth synchronizer clutch 94 while maintaining activation orengagement of the sixth synchronizer clutch 98. Eighth gear is also avirtual or blended gear ratio which is achieved by mixing or blendingthe highest speed gear (lowest gear ratio) of the sub-transmission A andthe higher speed gear (lower gear ratio) of the sub-transmission B.

Ninth gear is achieved by deactivating or disengaging the third frictionclutch 86 and the sixth synchronizer clutch 98 and activating orengaging the first friction clutch 82 while maintaining activation orengagement of the fourth synchronizer clutch 94. Ninth gear is an actualor pure gear ratio achieved by utilizing the highest speed gear (lowestgear ratio) of the sub-transmission A.

It will be appreciated that the foregoing explanation of operation andgear states of the first embodiment of the nine speed automatictransmission 10 is wholly and accurately applicable to operation of thesecond embodiment of the nine speed transmission 10′. Furthermore, theexplanation assumes that all clutches not specifically referenced in agiven gear ratio are inactive or disengaged. The explanation alsoassumes that during gear shifts between at least adjacent gear ratios, aclutch that is activated or engaged in both gear ratios will remainactivated or engaged during the shift. Finally, the foregoingexplanation assumes that downshifts follow essentially the oppositesequence of the corresponding up shifts and that several power on skipshifts, e.g., from first to third, are possible.

Referring now to FIG. 4, a diagrammatic representation of therelationship between the actual, physical gears and the virtual orblended gears of the nine speed automatic transmissions 10 and 10′ isprovided. As described above, second gear, fourth gear, sixth gear andeighth gear are virtual or blended gear ratios achieved by a utilizingvarious combinations of the gear ratios provided by the sub-transmissionA and the sub-transmission B whereas first gear, third gear, fifth gear,seventh gear and ninth gear are actual physical or pure gear ratiosprovided individually by either the sub-transmission A or thesub-transmission B. In FIG. 4, the horizontal axis represents neutraland greater distances above the neutral axis represent larger forwardnumerical gear ratios whereas greater distances below the neutral axisrepresent larger reverse numerical gear ratios. The left vertical axisrelates to pure gear ratios provided by the sub-transmission A and theright vertical axis relates to pure gear ratios provided by thesub-transmission B. Solid black circles represent physical or pure gearratios, open or white circles represent virtual or blended gear ratiosand cross-hatched circles represent reverse gear ratios. Note that thereare no reverse virtual or blended gear ratios.

The oblique line joining first gear and third gear is exemplary andillustrative of the fact that second gear is a virtual gear which is amixture or blend of the first gear ratio provided by thesub-transmission A and the third gear ratio provided by thesub-transmission B. The intersection of this oblique line with thecenter vertical line labeled A-B represents the blended second gearratio achieved by the sub-transmissions A and B which is between thefirst gear ratio and the third gear ratio.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A multiple speed automatic transmission comprising: an input member;an output member; a first, a second, a third and a fourth planetary gearassembly each having a first, a second and a third member; a first and asecond chain drive assembly each having a pair of sprockets and asprocket engaging chain; a first connecting member continuouslyconnecting the first member of the first planetary gear assembly with afirst of the pair of sprockets of the second chain drive assembly; asecond connecting member continuously connecting to the second member ofthe first planetary gear assembly; a third connecting membercontinuously connecting the second member of the first planetary gearassembly with a first of the pair of sprockets of the first chain driveassembly; a fourth connecting member continuously connecting to thesecond member of the second planetary gear assembly; a fifth connectingmember continuously connecting the third member of the second planetarygear assembly with the first member of the third planetary gearassembly; a sixth connecting member continuously connecting a second ofthe pair of sprockets of the second chain drive assembly with the firstmember of the second planetary gear assembly; a seventh connectingmember continuously connecting a second of the pair of sprockets of thefirst chain drive assembly with the first member of the fourth planetarygear assembly; an eighth connecting member continuously connecting thesecond member of the second planetary gear assembly with the secondmember of the third planetary gear assembly; a first torque transmittingdevice selectively connecting the first member of the first planetarygear assembly with the input member; a second torque transmitting deviceselectively connecting the second member of the first planetary gearassembly with the input member; a third torque transmitting deviceselectively connecting the third member of the first planetary gearassembly to the input member; a fourth torque transmitting deviceselectively connecting the third member of the first planetary gearassembly to a ground; a fifth torque transmitting device selectivelyconnecting the second member of the second planetary gear assembly withthe ground; a sixth torque transmitting device selectively connectingthe first member of the third planetary gear assembly and the thirdmember of the second planetary gear assembly with the ground; a seventhtorque transmitting device selectively connecting the first member ofthe second planetary gear assembly with the second member of the secondplanetary gear assembly; an eighth torque transmitting deviceselectively connecting the third member of the fourth planetary gearassembly with the ground; and a ninth torque transmitting deviceselectively connecting the third member of the fourth planetary gearassembly with the first member of the fourth planetary gear assembly,and wherein the output member is continuously connected to the thirdmember of the third planetary gear assembly and the second member of thefourth planetary gear assembly and the torque transmitting devices areengageable in combinations of at least two to establish at least nineforward gear ratios and one reverse gear ratio.
 2. The multiple speedautomatic transmission of claim 1 wherein the first members of theplanetary gear assemblies are sun gear members, the second members ofthe planetary gear assemblies are planet carrier members, and the thirdmembers of the planetary gear assemblies are ring gear members.
 3. Themultiple speed automatic transmission of claim 2 wherein the inputmember and the output member are shafts which define parallel,spaced-apart axes.
 4. The multiple speed automatic transmission of claim3 wherein the first, second, and third torque transmitting devices arefriction clutches, the fourth, fifth, sixth, and eighth torquetransmitting devices are brakes, and the seventh and ninth torquetransmitting devices are synchronizer clutches.